Seeding Particles

For different flow applications proper seeding tracers are needed. Depending on the application LaVision is offering several solid particles and liquids to be used in suitable seeding devices. The tracers are characterised by sufficient light scattering, perfect signal quality and very good traceabilty to the flow.

Applications:

air

flames/combustion

liquids

Seeding in air

HFSB soap fluidThe soap fluid is a colourless fluid for generating soap bubbles at an extremely high rate. Soap fluid and the corresponding seeding device are used especially where a big amount of particles are needed e.g. in wind tunnels and/or large scale PIV measurements. A proper seeding device is needed.

DEHS DEHS is an odourless and colourless liquid. It´s insoluble in water and the droplets have a long lifetime. For generating particles a proper seeding device is needed.

small density of 0.91 g/cm³

particle mean size less than 1 µm by using a LaVision seeding device

Fog fluid Fog fluid is an odourless fluid. For generating particles a proper seeding device is needed. Fog fluid and the corresponding seeding device are used especially where a big amount of particles are needed e.g. in wind tunnels.

small density of about 1.05 g/cm³

short lifetime

Product

Amount

HFSB Soap fluid

0.95 l

DEHS

0.5 l

DEHS

5 l

Fog fluid

5 l

Seeding in flames/combustion

Aerosil Due to its very porous structure of the agglomerated particles Aerosil is an ideal seeding material for PIV applications in combustion research:

primary particle size is 12 nm, agglomeration size in air several microns

very small density of 0.05 g/cm³ due to the “snow flake” structure of these particles

less velocity leak even in strongly accelerated flows

it can be used in hot gaseous environments with a temperature of up to 1800°C.

Titanium dioxide LaVision’s Titanium Dioxide is a surface treated, hydrophobic, highly insoluble and thermally stable material. Due to its submicron mean size and nanopowder form TiO2 is an ideal seeding material for PIV applications in combustion research:

the particles lead to a strong scatter of the laser light

particle size in clusters > 250 nm

density 3.9 – 4.2 g/cm³

highly insoluble and thermally stable up to 1800 °C

low agglomeration due to hydrophobic surface

Graphite: Due to its lubricating properties graphite particles offered by LaVision are an ideal seeding material for PIV applications in engines.

the particle size of several microns leads to a strong scatter of the laser light, particle mean size 3.5 µm

density 2.2 g/cm³

non-inflammable, only glowing

ignition temperature >450 °C

very good stability against pressure

Product

Amount

Aerosil

1 l

Titanium dioxide

0.5 kg

Graphite

0.5 kg

All these particles require a proper seeding device.

Seeding in liquids

Polyamide particles Due to its almost perfectly spherical particle shape the polyamide particles offered by LaVision are an ideal seeding material for PIV applications in liquids. A safe handling with these particles is guarenteed because of their non-toxic, non-water polluting nature.

the particle size of several microns leads to a strong scatter of the laser light

the particle size of several microns leads to a strong scatter of the laser light

very good stability against e.g. water, fuel, oil

Product

Amount

Glass hollow spheres, 9-13 µm, 1.1g/cm³

0.5 kg

Glass hollow spheres SC, 10 µm, 1.7 g/cm³

0.5 kg

Ceramic hollow spheres (SC), 100 µm, 1.1 g/cm³

0.5 kg

Fluorescent particles: Fluorescent seeding particles are based on melamine resin, polystyrene or PMMA. The fluorescent dye (Rhodamine B or Rhodamine 6G) is homogeneously distributed over the entire particle volume. Especially in PIV applications with a high background light level fluorescent seeding particles can enhance the signal to noise ratio. The optics of receiving devices must be equipped with a suitable filter centered on the corresponding wavelength. For µPIV applications the fluorescence is essential to separate the particle signal from the background scatter light. To separate the light emitted from the particles an epi-fluorescent microscope with filter cube is required.